Since there is still a large percentage of controlled US airspace not covered by LiveATC's many volunteers, the odds are high that an accident aircraft's communications may not have been captured by LiveATC's feeds.
FlightAware.com is showing an active IFR flight for that aircraft on the day of the accident. From the looks of the track it was a run-of-the-mill IFR cross country (long distance) flight from Mississippi to Texas. The last reported altitude in FlightAware was 10,000 feet, which also seems to coincide with the preliminary NTSB accident report, found here:
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20080502X00582&key=1Based on the facts reported in the NTSB report this accident seems to be a mystery. ATC loses contact with the aircraft while in cruise. Aircraft continues on at level altitude. Radar contact is soon lost as the aircraft descends uncontrolled into a lake.
Normally aircraft do not crash while in level flight unless inadvertently flying into the heart of a thunderstorm. However the NTSB reported that the aircraft crashed in visual conditions (which incidentally conflicts with witness statements in the report).
